Isocitrate dehydrogenase 1 (IDH1, protein accession number NP_005887.2) is an enzyme whose normal function is to convert isocitrate to α-ketoglutarate. Mutated forms of this enzyme, most commonly IDH1(R132H) in which arginine 132 is mutated to histidine, are common in a variety of cancers including glioma, cholangiocarcinoma, chondrosarcoma, and AML. The IDH1(R132H, R132C, R132S) mutation and similar IDH1 mutations are gain-of-function mutations which result in the enzyme gaining the ability to catalyze the NADPH-dependent reduction of α-ketoglutarate to R-2-hydroxyglutarate (2HG). Elevated levels of 2HG have been shown to lead to an elevated risk of brain tumors in humans. 2HG is described as an oncometabolite, and a proposed mode of action is that it leads to hypermethylation of histones and causing inhibited cell differentiation and the development of cancerous cells.
Mutant IDH1 is an attractive target for anti-cancer therapeutics. Inhibition of mutant IDH1 reduces levels of 2HG. It is expected that lower 2HG levels will result in fewer undifferentiated cancer cells. Furthermore, inhibition of mutant IDH1 is expected to have little effect on non-cancerous cells, as these cells do not express the IDH1 mutation resulting in lower toxicity than typical cytotoxic anticancer agents.
For these reasons mutant IDH1 inhibitors are needed as anti-cancer therapeutics. This disclosure provides mutant IDH1 inhibitors and possesses additional advantages which are set forth in the following descriptions